Fundamentally the function of a gear box is to change the speed from that of an input shaft to that of an output shaft whilst allowing the transmission of torque between the shafts. Typically gear boxes comprise several gear clusters or gear trains that can be coupled to each other in various configurations to give selected gear ratios of the input and output shafts.
One of the disadvantages of most conventional gear boxes is that the gear ratios that can be selected are fixed at certain preselected ratios that may or may not be optimum to derive maximum torque from the engine or other drive source. In motor vehicles it is desirable to maintain the internal combustion engine at an optimum speed, both from the point of view of fuel economy and to obtain maximum torque. Likewise, it is preferable to maintain the speed of certain types of electric motors within a prescribed RPM range in order to develop maximum torque efficiency. However this is not possible with a conventional gearbox and a compromise is made using preselected gear ratios.
Another disadvantage of most conventional gear boxes is that they are generally bulky and occupy a considerable volume in the drive train. A still further disadvantage of most conventional gear boxes is that the load must be disconnected when changing gears and when starting the engine or motor driving the load.
The present invention was developed with a view to providing a variable ratio power transmission that is able to overcome one or more of the above-noted disadvantages of the prior art.